A wide range of implantable medical devices are provided for surgical implantation into humans or animals. One common example is the cardiac pacemaker. Another is the implantable cardioverter defibrillator. Other examples include devices for stimulating or sensing portions of the brain, spinal cord, muscles, bones, nerves, glands or other body organs or tissues.
Implantable medical devices, particularly pacemakers, are often configured to be used in conjunction with an external programmer device which allows a physician to display information sensed by the device. For a pacemaker, for example, the external programmer device may operate to display electrical cardiac signals detected by the pacemaker in the form of IEGM's and ECG's. An IEGM is a graphic depiction of electrical signals emitted by active cardiac tissue as detected by electrodes placed on or in the heart. An ECG is also a graphic depiction of the electrical signals emitted by active cardiac tissue but is detected using electrodes placed on the body surface rather than in or on the heart itself.
One example of an external programmer that displays IEGM's and ECG's is an analyzer-programmer system (APS) identified as the APS II system which is provided by Pacesetter Inc. of Sylmar, Calif. More specifically, the APS II system displays IEGM's and surface ECG's in conjunction with icons representative of paced and sensed atrial and ventricular events such as atrial stimulus, ventricular stimulus, atrial activity outside atrial refractory/blanking period, ventricular activity outside ventricular refractory/blanking period, and the length of atrial refractory period. The APS II system also displays variable length horizontal lines representative of the length of the atrial and ventricular refractory periods and also displays numerical values indicative of measured intervals between the atrial and ventricular events. Further information regarding the detection and display of IEGM signals may be found in U.S. Pat. No. 5,620,473 to John W. Poore entitled "Calibration System for Pacemaker-Generated Intracardiac Electrogram" which provides for the display and calibration of IEGM signals. U.S. Pat. No. 5,620,473 is also incorporated by reference herein.
Other components of the APS II system of Pacesetter Inc. operate to allow a physician to program the operation of the pacemaker to, for example, control the specific parameters by which the pacemaker senses the IEGM signals and the manner by which the pacemaker detects arrhythmia conditions within the heart and responds thereto. For example, the APS II system allows the physician to specify the sensitivity with which the pacemaker senses electrical signals within the heart and to further specify the amount of electrical energy to be employed for pacing the heart in circumstances where expected heart signals are not sensed. Still other components of the APS II system operate to display a variety of diagnostic information received from the pacemaker. More specifically, the APS II system displays the different types of diagnostic information set forth in TABLE I.
TABLE I ______________________________________ EVENT NAME EVENT TYPE ______________________________________ AV A-pulse followed by a V-pulse AR A-pulse followed by an R-wave PVE Premature ventricular event PV P-wave followed by a V-pulse PR P-wave followed by an R-wave P@MTR-V P-wave at maximum tracking rate followed by a V-pulse P@MTR-R P-wave at maximum tracking rate followed by a R-wave MAGNET Magnet placed over the implanted device--either singly or in combination with an external telemetry system ______________________________________
U.S. Pat. No. 5,431,691 to Snell et al. entitled "Method and System for Recording and Displaying a Sequential Series of Pacing Events" provides a detailed description of the operation of the APS II system of Pacesetter Inc. including a description of the processing and displaying of the diagnostic information set forth in TABLE I. In particular, the Snell et al. patent describes a technique whereby the pacemaker processes and records diagnostic data in the form of "event records" which allow the data to be efficiently stored within the pacemaker, transmitted to the APS II system, and displayed. U.S. Pat. No. 5,431,691 to Snell et al. is incorporated by reference herein.
As can be seen from TABLE I, the events processed by the APS II system are primarily events sensed within the heart of the patient. Event records containing information pertaining to those events are recorded within the pacemaker for subsequent transmission to the external programmer for display thereon in a variety of formats including event record displays, event bar graphs, rate bar graphs, rate time graphs, and event time graphs, each under the control of the physician operating the external programmer. More specifically, the event record display presents the various detected events of TABLE I and the corresponding pacing rate with respect to the time of the occurrence of the event. For periods of time while the pacemaker is in a dual-chamber mode (such as DDD, DDI etc.), the events presented include PV, PR, AV (or V when the mode is VDDR or VDD), AR and PVC (premature ventricular contraction). For periods of time while the pacemaker is in a single-chamber mode (such as VVI, AAI etc.), the events are presented merely as paced or sensed. The event bar graph presents a histogram of different event types listing the total number of counts of each event type for a selected period of time. The event time graph presents histograms of event types vs. time of event occurrence. The rate bar graph presents histograms of sensed and paced events vs. their rate. The rate time graph presents histograms of rates vs. times. Further information regarding the different displays may be found in the Snell et al. patent.
As can be appreciated, a wide range of useful information, particularly directed to events sensed within the heart, is thereby provided to assist the physician in rendering a diagnosis as to any arrhythmia or other condition the patient may exhibit or to assist the physician in making choices as to adjusting various parameters by which the pacemaker monitors and paces the heart. The information is displayed in a variety of convenient graphical formats to help the physician visualize the information quickly and easily to facilitate prompt and accurate diagnoses.
The parent application referenced above describes various improvements to the APS II system. For example, the parent application describes improvements wherein the system records and displays numerous additional types of diagnostic data including data pertaining to 1) operational events triggered within the pacemaker as a result of the condition of the patient (such as automode switching events) and 2) operational events triggered within the pacemaker as a result of the condition of the pacemaker itself (such as battery tests or lead fault detection tests). The additional diagnostic data is displayed as part of one or more of the aforementioned event record displays, event bar graphs, rate bar graphs, rate time graphs, and event time graphs.
Although the system described in the parent application, which displays the additional diagnostic information in conjunction with event records, represents an improvement over the ASP II system, further room for improvement remains. In particular, it would be desirable to also display at least some of the additional types of event record diagnostic information in conjunction with the aforementioned IEGM and surface ECG displays to allow the physician to view the additional event record diagnostic information while simultaneously viewing IEGM's or ECG's and it is primarily to that end that the present invention is directed.